The invention relates to a pressure sensor or switch for determining the air pressure in the interior of tubeless tires of motor vehicles mounted on a rim, wherein the housing of the pressure sensor or switch penetrates a corresponding recess of a rim wall and is fastened at the rim in an airtight manner of fastening devices.
Such a pressure sensor, as is known e.g. from DE-OS 35 23 774, serves to monitor the air pressure in a tubeless motor vehicle tire and to send an electrical signal when the air pressure in the tire diverges from the normal state, particularly when the air pressure drops as a result of a defect in the tire wall.
In order to fasten such pressure sensors or switches the housing conventionally comprises an external thread and is inserted into a recess of the rim, wherein the housing is then clamped against the rim wall so as to be airtight by a nut secured on the thread.
This type of fastening has the disadvantage that the pressure sensor or switch projects relatively far over the rim wall due to the required thread length. This is undesirable in technical respects relating to mounting and involves the risk of damage when changing tires. But, above all, the detection interval for the signal transmission from the sensor to a receiver, which is fixed with respect to rotation relative to the latter, is reduced because of the metallic nut, which damps the resonant circuit provided for the signal transmission.